Analyzes the androgenic and estrogenic effects of testosterone (T) in stimulating growth and the production of growth hormone (GH) and IGF1 at puberty. Boys with delayed puberty will be treated either with T or dihydrotestosterone (DHT). Those effects seen with T treatment but not with DHT are attributable to estradiol, whereas the effects of DHT are considered purely androgenic. Parameters to be followed include height velocity, bone age, spontaneous and stimulated plasma GH, and IGF1.